氢气不仅可以在空气中燃烧，还可以在氯气中燃烧，反应方程式为H2+Cl2===(点燃)2HCl ，若用“○”表示氯原子，“●”表示氢原子，则上述反应可表示为
A：
B：
C：
D：
Yesterday was Sunday. Tom was at home. He got up at six o’clock in the morning. He had rice for breakfast. At eight he helped his mother do the housework. At nine he watched TV with his father. He cooked fish for lunch. At four in the afternoon he washed his clothes. He went to bed at ten in the evening.
一盒彩色胶卷最多能拍36张照片，照这样计算，15盒胶卷最多可以拍____张照片。
